diff --git a/mail/config/postfix-main.cf b/mail/config/postfix-main.cf
new file mode 100644
index 0000000..378644a
--- /dev/null
+++ b/mail/config/postfix-main.cf
@@ -0,0 +1,3 @@
+gerrit_sender_check = check_client_access hash:/tmp/docker-mailserver/gerrit-client.access, reject
+smtpd_restriction_classes = gerrit_sender_check
+dms_smtpd_sender_restrictions = check_sender_access hash:/tmp/docker-mailserver/user.access, permit_sasl_authenticated, permit_mynetworks, reject_unknown_sender_domain